Positron Emission Computed Tomography (PET) apparatuses are nuclear medicine imaging apparatuses that acquire data relating to pair annihilation events from a subject to which a medicine labeled with positron emission nuclide is administered, to reconstruct a PET image serving as a nuclear medicine image. PET apparatuses reconstruct a PET image indicating tissue distribution of the subject that has taken the medicine, using the phenomenon that two photons (two gamma rays) are emitted in opposite directions when a positron emitted from the medicine is connected with an electron and annihilated.
Generally, the amount of the accumulated medicine differs according to the region of the subject. For this reason, for example, when the time for acquiring gamma rays for each imaging position is fixed in PET imaging, the count values of gamma rays acquired by the PET apparatus become non-uniform between the imaging positions. This non-uniformity may result in non-uniformity in the noise level of the PET image, and deterioration in the inspection efficiency.